Select Git revision
parse_simple.c
Alexei Starovoitov
authored and
David S. Miller
committed
parse_simple.c - packet parser exapmle with single length check that filters out udp packets for port 9 parse_varlen.c - variable length parser that understand multiple vlan headers, ipip, ipip6 and ip options to filter out udp or tcp packets on port 9. The packet is parsed layer by layer with multitple length checks. parse_ldabs.c - classic style of packet parsing using LD_ABS instruction. Same functionality as parse_simple. simple = 24.1Mpps per core varlen = 22.7Mpps ldabs = 21.4Mpps Parser with LD_ABS instructions is slower than full direct access parser which does more packet accesses and checks. These examples demonstrate the choice bpf program authors can make between flexibility of the parser vs speed. Signed-off-by:Alexei Starovoitov <ast@kernel.org> Signed-off-by:
parse_simple.c 1.25 KiB
/* Copyright (c) 2016 Facebook
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*/
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/in.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <uapi/linux/bpf.h>
#include <net/ip.h>
#include "bpf_helpers.h"
#define DEFAULT_PKTGEN_UDP_PORT 9
/* copy of 'struct ethhdr' without __packed */
struct eth_hdr {
unsigned char h_dest[ETH_ALEN];
unsigned char h_source[ETH_ALEN];
unsigned short h_proto;
};
SEC("simple")
int handle_ingress(struct __sk_buff *skb)
{
void *data = (void *)(long)skb->data;
struct eth_hdr *eth = data;
struct iphdr *iph = data + sizeof(*eth);
struct udphdr *udp = data + sizeof(*eth) + sizeof(*iph);
void *data_end = (void *)(long)skb->data_end;
/* single length check */
if (data + sizeof(*eth) + sizeof(*iph) + sizeof(*udp) > data_end)
return 0;
if (eth->h_proto != htons(ETH_P_IP))
return 0;
if (iph->protocol != IPPROTO_UDP || iph->ihl != 5)
return 0;
if (ip_is_fragment(iph))
return 0;
if (udp->dest == htons(DEFAULT_PKTGEN_UDP_PORT))
return TC_ACT_SHOT;
return 0;
}
char _license[] SEC("license") = "GPL";